[ODRHash] Revert r307743 which reverted r307720

Reapply r307720 to allow processing of constructors and destructors.  Reuse
the diagnostics for CXXMethodDecl for them.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@308077 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed